A method and system for enhancing photoacoustic signal quality using multi-laser synergistic acoustics

Abstract

This invention provides a method and system for enhancing the quality of photoacoustic signals using multi-laser synergistic acoustic emission. The method includes acquiring external sound signals and converting them into electrical signals; performing bandpass filtering on the electrical signals at different frequencies to obtain filtered electrical signals; modulating the filtered electrical signals according to their characteristics to obtain laser control information; and controlling the lasers to output laser signals based on the laser control information, thereby illuminating multiple laser signals onto the ear. By using two or more acoustic laser beams to illuminate the ear, a higher quality sound signal is generated in the ear.

Description

Technical Field

[0001] This invention relates to the field of laser acoustics technology, and more specifically, to a method and system for enhancing photoacoustic signal quality using multi-laser synergistic acoustics. Background Technology

[0002] Laser acoustics is a technology that uses lasers to generate sound on a specific medium. Based on different acoustic mechanisms, laser acoustics can be divided into three different types: laser thermal expansion acoustics, vaporization acoustics, and photo-breakdown acoustics.

[0003] Laser thermal expansion-induced acoustics is a product of the interaction between laser and matter. When a laser irradiates the surface of a material, photons interact with the molecules of the material, causing molecular vibrations. The laser energy is absorbed by the material and converted into heat energy, leading to a local increase in the temperature of the material. As a result, the material undergoes thermal expansion, which propagates outward in the form of waves, thereby generating sound waves or sound fields.

[0004] The acoustic signal excited by a laser is determined by the laser pulse spectrum function, laser energy, and laser spot radius. In other words, by adjusting parameters such as the laser pulse spectrum function, laser energy, and laser spot radius, specific sounds can be generated in a medium.

[0005] However, problems arise in controlling the laser output, namely, the inability to precisely control the waveform of the laser output. The main reasons include the laser's working principle, design complexity, limitations of control technology, and the influence of environmental factors. The following is a detailed analysis of these reasons:

[0006] 1. The complexity of laser operating principles makes precise control of the laser output waveform impossible. Lasers operate by exciting atoms or molecules into an excited state, then releasing photons through stimulated emission. This process involves transitions between multiple energy levels and is influenced by various factors, such as the stability of the excitation source and the properties of the laser medium. Simultaneously, the optical cavity within the laser is formed by mirrors, causing photons to be reflected and amplified multiple times before the final laser output. The feedback mechanism of the optical cavity can lead to waveform instability during this process. Therefore, the complexity of laser operating principles makes precise control of the laser output waveform impossible.

[0007] 2. Limitations in laser control technology prevent precise control of the laser output waveform. Despite continuous advancements in modern control technology, limitations remain. For example, the precision and response time of the control circuit can affect the accurate control of the laser output waveform.

[0008] 3. Environmental factors can prevent precise control over the waveform of the laser output. Lasers are sensitive to temperature changes; temperature fluctuations can alter the properties of the laser medium, affecting the stability of the output waveform. External vibrations and shocks can cause displacement or damage to internal laser components, thus affecting the accuracy of the output waveform.

[0009] Based on the thermal expansion-induced sound mechanism described above, since the waveform of the laser output from the laser cannot be precisely controlled, the sound signal excited in the ear by a single laser beam suffers from frequency response-related distortion.

[0010] Therefore, in order to generate clearer, more natural, powerful, and high-fidelity sound signals in the ear, it is necessary to improve the precision of the control over the laser output waveform. Summary of the Invention

[0011] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for enhancing photoacoustic signal quality using multi-laser synergistic acoustics.

[0012] A photoacoustic signal quality enhancement system employing multi-laser coordinated acoustic modulation, provided by the present invention, comprises:

[0013] Sound acquisition module: Acquires external sound signals and converts the acquired external sound signals into electrical signals;

[0014] Multiple different bandpass filters are electrically connected to the sound acquisition module to perform bandpass filtering on the electrical signal at different frequencies, thereby obtaining the filtered electrical signal.

[0015] Multiple modulators are electrically connected to the bandpass filter one by one, and modulate the filtered electrical signal according to the characteristics of the filtered electrical signal to obtain laser control information.

[0016] Multiple lasers are electrically connected to the modulator one by one, and laser signals are generated according to the laser control information. The laser signals are irradiated at the ear position.

[0017] Furthermore, the multiple different bandpass filters include two: a low-frequency bandpass filter and a high-frequency bandpass filter.

[0018] Furthermore, the bandwidth parameters of the low-frequency bandpass filter include 20Hz-2000Hz, and the bandwidth parameters of the high-frequency bandpass filter include 2000Hz-20000Hz.

[0019] Furthermore, the multiple laser signals are time-synchronized, or the time difference between the multiple laser signals is less than the time difference for the ear to distinguish sounds.

[0020] Furthermore, the sound acquisition module acquires external sound signals by acquiring stereo channel signals or surround sound channel signals, wherein the stereo channel signals or surround sound channel signals include multiple channel signals, and outputs corresponding electrical signals respectively.

[0021] Furthermore, the stereo channel signal includes a left channel signal and a right channel signal, or it includes a left channel signal, a right channel signal, and a subwoofer signal.

[0022] Furthermore, the surround sound channel signals include left channel signals, center channel signals, right channel signals, left surround channel signals, right surround channel signals, and subwoofer channel signals, or include left channel signals, center channel signals, right channel signals, left surround channel signals, right surround channel signals, subwoofer channel signals, side left channel signals, side right channel signals, and sky channel signals.

[0023] Furthermore, after acquiring the stereo channel signal or the surround sound channel signal, the generated multiple laser signals are irradiated onto the corresponding left or right ear position.

[0024] Furthermore, the expression for the laser-to-acoustic signal transfer function H(ω) is as follows:

[0025]

[0026] In the above formula, e is the natural constant, j is the imaginary unit, r is the distance from the receiver to the sound source, θ is the observation angle of the receiver, ω is the laser angular frequency, μ is the absorption coefficient of the medium to the laser, and a is the radius of the laser spot.

[0027] A photoacoustic signal quality enhancement method using multi-laser synergistic acoustic modulation provided by the present invention includes:

[0028] Step S1: Collect external sound signals and convert the collected external sound signals into electrical signals;

[0029] Step S2: Perform bandpass filtering on the electrical signal at different frequencies to obtain the filtered electrical signal;

[0030] Step S3: Modulate the filtered electrical signals according to their characteristics to obtain laser control information;

[0031] Step S4: Control the laser to output laser signals according to the laser control information, and irradiate multiple laser signals onto the ear position.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention can be applied to laser-induced sound hearing aids or other voice communication systems that utilize the mechanism of laser thermal expansion to induce sound. It employs two or more laser beams to irradiate the ear, thereby generating a higher quality sound signal in the ear. Attached Figure Description

[0034] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0035] Figure 1 This is a schematic diagram of the first embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the second embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the third embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the fourth embodiment of the present invention. Detailed Implementation

[0039] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0040] Example 1

[0041] like Figure 1 As shown, the present invention provides a photoacoustic signal quality enhancement system using multi-laser synergistic acoustics, comprising: a sound acquisition module 1, a low-frequency bandpass filter 21, a high-frequency bandpass filter 22, a modulator 1 31, a modulator 2 32, a laser 1 41, and a laser 2 42.

[0042] The sound acquisition module 1 acquires external sound signals and converts them into electrical signals, which are then transmitted to the low-frequency bandpass filter 21 and the high-frequency bandpass filter 22, respectively. The sound acquisition module 1 can use a microphone, which can be a single microphone or microphone array installed inside the device, or an external wired or wireless microphone.

[0043] The low-frequency bandpass filter 21 performs low-frequency bandpass filtering on the electrical signal. The bandwidth parameter of the low-frequency bandpass can be adjusted as needed, with a typical value of 20Hz-2000Hz. The high-frequency bandpass filter 22 performs high-frequency bandpass filtering on the electrical signal. The bandwidth parameter of the high-frequency bandpass can be adjusted as needed, with a typical value of 2000Hz-20000Hz.

[0044] Modulator 1 31 modulates the electrical signal based on the characteristics of the low-frequency bandpass filtered signal to obtain the first laser control information, and modulator 2 32 modulates the electrical signal based on the characteristics of the high-frequency bandpass filtered signal to obtain the second laser control information.

[0045] The process by which the controller converts electrical signals into laser control signals includes:

[0046] Step S1: Obtain the electrical signal of the sound signal.

[0047] Step S2: Perform time-frequency analysis on the electrical signal.

[0048] Step S3: Extract acoustic signal features based on the time-frequency analysis results.

[0049] Step S4: Modulate and generate a control signal based on the extracted acoustic signal features.

[0050] Step S5: Control the laser to output acoustic laser according to the control signal.

[0051] In step S1, the method for acquiring the electrical signal includes real-time reception, and the signal strength can be amplified as needed before the electrical signal is output to the time-frequency analysis.

[0052] In step S2, the time-frequency analysis method includes analyzing the electrical signal in both the time and frequency domains. The time domain focuses on analyzing the signal strength, while the frequency domain focuses on analyzing the signal spectrum. The maximum processing delay time in this step is 1 millisecond.

[0053] In step S3, the method for extracting electrical signal features includes filtering the sound signal. The filtering range can be set, and a typical value can be referenced to the normal hearing range, i.e., 20Hz-20000Hz. Feature extraction is performed on the filtered electrical signal. The features include the start time of the positive pulse of the electrical signal, the time when the positive pulse reaches its maximum amplitude, the maximum amplitude, and the spectrum of the electrical signal, where the maximum amplitude is the voltage value.

[0054] In step S4, the modulated control signal includes a pulse sequence. In the pulse sequence, the start time of each pulse is the start time of the positive electrical signal pulse, and the end time is the time when the positive electrical signal pulse reaches its maximum amplitude. In the pulse sequence, the amplitude of each pulse is the normalized amplitude of the positive electrical signal pulse multiplied by an amplification parameter. The normalized amplitude can be the normalized result of the maximum amplitude of the positive electrical signal pulse, the normalized result of the peak signal amplitude on the electrical signal spectrum, or the normalized result of the control voltage corresponding to the maximum output amplitude of the acoustic laser. The amplification parameter is adjusted according to the type of laser outputting the acoustic laser.

[0055] Laser 1 41 generates a first laser signal 51 based on the control information of the first laser, and laser 2 42 generates a second laser signal 52 based on the control information of the second laser. The first laser signal 51 and the second laser signal 52 are irradiated at the ear position of the user 6 (right ear position 61 in the figure). The two acoustic lasers irradiate the human ear in a coordinated manner, which can excite a clearer, more natural, powerful, and high-fidelity sound signal in the human ear. The first laser signal 51 and the second laser signal 52 must be synchronized in time, and the synchronization time difference is less than the time difference for the human ear to distinguish the sound (also known as the auditory discrimination threshold, typically 50 milliseconds).

[0056] The equation for laser-induced acoustics based on thermal expansion is as follows:

[0057]

[0058] In the above formula, p is the sound pressure caused by laser thermal expansion, c is the sound velocity, and C p Let β be the specific heat capacity of the medium, I(x,y,z,t) be the laser energy absorbed by the medium, where x,y,z are the three-dimensional coordinates of the acoustic signal receiving point, t is time, and β is the coefficient of thermal expansion of the medium.

[0059] The above equation is a partial differential equation, and one solution to this equation can be written in the following form:

[0060]

[0061] In the above formula, P(ω) is the spectral intensity of the photoacoustic signal, ω is the laser angular frequency, I0(ω) is the spectral function of the laser pulse, A is the refractive index of the laser in the medium, P0 is the laser energy, β is the coefficient of thermal expansion of the medium, and C... p Let H(ω) be the specific heat capacity of the medium, and H(ω) represent the transfer function from the laser signal to the acoustic signal, expressed as follows:

[0062]

[0063] In the above formula, e is the natural constant, j is the imaginary unit, r is the distance from the receiver to the sound source, θ is the observation angle of the receiver, ω is the laser angular frequency, μ is the absorption coefficient of the medium to the laser, and a is the radius of the laser spot.

[0064] Example 2

[0065] like Figure 2As shown, this invention also provides a photoacoustic signal quality enhancement system employing multi-laser synergistic acoustic enhancement. Based on Embodiment 1, it uses more laser signals to illuminate the ear location; that is, the bandpass filter also includes other bandpass filters n23 with different bandwidths, as well as corresponding modulators n33 and lasers n43. The synergistic illumination of the ear by more acoustic lasers can generate a clearer, more natural, powerful, and high-fidelity sound signal.

[0066] Example 3

[0067] like Figure 3 As shown, the present invention also provides a photoacoustic signal quality enhancement system employing multi-laser synergistic acoustics. Based on Embodiment 1 or Embodiment 2, the sound acquisition module 1 acquires stereo channel signals. The stereo channel signals include 2.0 channel signals and 2.1 channel signals.

[0068] The 2.0 channel signal includes the left and right channel signals, while the 2.1 channel signal includes the left, right, and subwoofer signals. Each signal is configured with a corresponding filter, modulator, and laser. Taking the 2.1 channel signal as an example, the right channel signal, after filtering, outputs the first laser signal 51 to the right ear position 61 via modulator 31 and laser 41. The left channel signal, after filtering, outputs the third laser signal 53 to the left ear position 62 via modulator 33 and laser 43. The subwoofer signal, after filtering, outputs the second laser signal 52 to the right ear position 61 via modulator 32 and laser 42, and the fourth laser signal 54 to the left ear position 62 via modulator 34 and laser 44, thus achieving a stereo effect.

[0069] Example 4

[0070] like Figure 4 As shown, this invention also provides a photoacoustic signal quality enhancement system employing multi-laser synergistic acoustic projection. Based on Embodiment 1 or Embodiment 2, the sound acquisition module 1 acquires surround sound channel signals. The surround sound channel signals can be 5.1 channel signals, 7.1 channel signals, or their advanced versions such as 5.1.2, 7.1.4, etc. The surround sound channel signals include left channel signals, center channel signals, right channel signals, left surround channel signals, right surround channel signals, and subwoofer channel signals; or, they include left channel signals, center channel signals, right channel signals, left surround channel signals, right surround channel signals, subwoofer channel signals, side left channel signals, side right channel signals, and sky channel signals. Referring to Embodiment 3, except for the laser signals corresponding to the left channel signals, right channel signals, left surround channel signals, and right surround channel signals which need to illuminate their respective ear positions, the laser signals corresponding to the remaining signals need to simultaneously illuminate both left and right ear positions to achieve a surround sound effect.

[0071] This invention also provides a method for enhancing the quality of photoacoustic signals using multi-laser synergistic acoustics, comprising:

[0072] Step S1: Collect external sound signals and convert the collected external sound signals into electrical signals.

[0073] Step S2: Perform bandpass filtering on the electrical signal at different frequencies to obtain the filtered electrical signal.

[0074] Step S3: Modulate the filtered electrical signals according to their characteristics to obtain laser control information.

[0075] Step S4: Control the laser to output laser signals according to the laser control information, and irradiate multiple laser signals onto the ear position.

[0076] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0077] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A photoacoustic signal quality enhancement system employing multi-laser synergistic acoustic modulation, characterized in that, include: Sound acquisition module: Acquires external sound signals and converts the acquired external sound signals into electrical signals; Multiple different bandpass filters are electrically connected to the sound acquisition module to perform bandpass filtering on the electrical signal at different frequencies, thereby obtaining the filtered electrical signal. Multiple modulators are electrically connected to the bandpass filter one by one, and modulate the filtered electrical signal according to the characteristics of the filtered electrical signal to obtain laser control information. Multiple lasers are electrically connected to the modulator one by one, and laser signals are generated according to laser control information. The laser signals are irradiated at the ear position. The multiple different bandpass filters include two: a low-frequency bandpass filter and a high-frequency bandpass filter; The bandwidth parameters of the low-frequency bandpass filter include 20Hz-2000Hz, and the bandwidth parameters of the high-frequency bandpass filter include 2000Hz-20000Hz. The multiple laser signals are time-synchronized, or the time difference between the multiple laser signals is less than the time difference for the ear to distinguish sounds; transfer function The expression is as follows: In the above formula, r is The distance from the receiver to the sound source, θ For the observation angle at the receiving end, ω The laser angular frequency, μ The absorption coefficient of the medium for laser light. a Let be the radius of the laser spot. c The speed of sound.

2. The photoacoustic signal quality enhancement system employing multi-laser synergistic acoustics as described in claim 1, characterized in that, The sound acquisition module acquires external sound signals by acquiring stereo channel signals or surround sound channel signals, wherein the stereo channel signals or surround sound channel signals include multiple channel signals, and each outputs a corresponding electrical signal.

3. The photoacoustic signal quality enhancement system employing multi-laser synergistic acoustics as described in claim 2, characterized in that, The stereo channel signal includes a left channel signal and a right channel signal, or it includes a left channel signal, a right channel signal, and a subwoofer signal.

4. The photoacoustic signal quality enhancement system employing multi-laser synergistic acoustics as described in claim 2, characterized in that, The surround sound channel signals include the left channel signal, center channel signal, right channel signal, left surround channel signal, right surround channel signal, and subwoofer channel signal, or include the left channel signal, center channel signal, right channel signal, left surround channel signal, right surround channel signal, subwoofer channel signal, side left channel signal, side right channel signal, and sky channel signal.

5. The photoacoustic signal quality enhancement system employing multi-laser synergistic acoustics as described in claim 2, characterized in that, After acquiring the stereo channel signal or the surround sound channel signal, the generated multiple laser signals are irradiated onto the corresponding left or right ear position.

6. A method for enhancing the quality of photoacoustic signals using multi-laser synergistic acoustics, characterized in that, include: Step S1: Collect external sound signals and convert the collected external sound signals into electrical signals; Step S2: Apply multiple different bandpass filters to the electrical signal at different frequencies to obtain the filtered electrical signal; Step S3: Modulate the filtered electrical signals according to their characteristics to obtain laser control information; Step S4: Control the laser to output laser signals according to the laser control information, and irradiate multiple laser signals onto the ear position; The multiple different bandpass filters include two: a low-frequency bandpass filter and a high-frequency bandpass filter; The bandwidth parameters of the low-frequency bandpass filter include 20Hz-2000Hz, and the bandwidth parameters of the high-frequency bandpass filter include 2000Hz-20000Hz. The multiple laser signals are time-synchronized, or the time difference between the multiple laser signals is less than the time difference for the ear to distinguish sounds; transfer function The expression is as follows: In the above formula, r is The distance from the receiver to the sound source, θ For the observation angle at the receiving end, ω The laser angular frequency, μ The absorption coefficient of the medium for laser light. a Let be the radius of the laser spot. c The speed of sound.

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